Remember also that Tailem Bend VOR is only about 5 nm NE of Brooklands Air Park (YBAK) near Wellington. It is on the Adelaide VNC without an allocated CTAF so shouldn't aircraft operating within 10nm and below say 5000' (and therefore in the vicinity of YBAK) be on 126.7 anyway?
Correct.
So
Dexta: your point 3. is correct.
And if YBAK had a discrete CTAF, then
"the various training organisations and flying schools for IFR approach practice" would
"switch to the discrete CTAF and coordinate with each aircraft at what levels you would operate, how long, intentions etc."
Simple.